Reduction drive



Dec. 24, 1940. A KORFF 2,225,957

REDUCTION DRIVE Filed Aug. 26, 1938 2 Sheets-Sheet 1 462m a w ATTORNEY.

Deer 24, 1940. KORFF REDUCTION DRIVE 2.Sheets-Sheet 2 Filed Aug 26, 1938ATTORNEY.

Patented Dec. 24, 1940 UNITED STATES REDUCTION DRIVE Abram Korfl,Chicago, Ill., assignor to Merkle- Korfl Gear Company, Chicago, 111., acorpora- 7 tion of Illinois Application August 26, 1938, Serial No.226,931

'7 Claims.

5 ing connection in which they are adapted to be used.

An important object of the invention is therefore in the provision ofspeed reduction gearing in which the high speed of a motor is materiallyreduced for power application.

A further object of the invention is in the provision of a reductiongearing in which the high speed of a low power motor can be utilized toproduce a high driving torque at low speed.

A further object of the invention is in the provision of worm anddifferential spur gearing which are combined to transform small torqueat high speed to high torque at low speed.

A still further object of the invention is in the provision of areduction drive in which gearing is mounted on a shaft in a closedcasing to produce the desired reduction in speed but with a frangiblejoint outside of the casing which protects the gearing and is easilyaccessible from the outside without opening the gear case.

Other objects of the invention will appear hereinafter, the preferredconstruction being illustrated in the accompanying drawings in which iFig. 1 is an elevation with one cover plate of the gear casing removed,showing the invention; and

Fig. 2 is a sectional view through the gearing showing the drive motorin elevation.

In providing a slow speed drive mechanism which requires considerablepower it is desirable to use a high speed electric motor of low power inwhich the necessary and efficient operation of the motor is reduced to ausable amount by a reduction gearing.

In the present invention this reduction is obtained first by drivepulleys, then by a worm gear, and then by a planetary type of reductiongearing which terminates in a driving shaft upon one end of the housing6.

At the top of the combined casing and housing is a suitable support forthe base of an electric motor I I having a shaft |2projecting at one endthereof parallel to the shaft l and upon these shaft extremities aresecured combination speed reduction pulleys I3 for variously engaging adriving belt l4 for connecting them.

Within the casing 5 and mounted upon the shaft 1 is a gear l5 havingteeth in engagement with the worm gear 9 secured to the drive shaft l0.At the center of this gear. and formed. integral with it at one side isan eccentric bearing portion IS with a corresponding shoulder l1.

Mounted upon the bearing portion l6 and freely rotatable thereon is adouble gear 18 having a large circular gear l9 and a smaller concentricgear 20. Extending inwardly from the casing is an internally toothedgearing 2| Which is fixed in place and larger than the gear l9 buthaving its teeth opposite those of the gear l9 so that as the doublegear 18 is rotated upon the eccentric Hi the teeth I 9 are caused toroll into engagement with the teeth of the gear 2| but the teeth beingless in number will thereupon cause a differential movement of. thedouble gear l8.

Also mounted upon the shaft 1 and abutting the eccentric I6 at one sideis a gear member 22 having a toothed portion 23 overhanging and in linewith the teeth 20 of the double gear l8 engaged thereby as the doublegear member I8 is rotated by its eccentric I6. Thus the reduction in thedrive between the gear l5 and the gear member 22 depends upon thedifference in teeth between the gears [Band 2| on one side and the gears20 and 23 on the other side, and the eccentric l6 .causesthe rollingengagement of the gear member IS. with both of the internally toothedgears 2| and 23.

Extending laterally from the outer side of the gear member 22 is acentral bearing portion 24 seated in an opening 25 of an end plate 26for closing the open side of the gear casing and suitably held inplace'by fastening screws 21, thus forming a fixed bearing for this endof the shaft 1,.

The extremity of the shaft 1 projects through the plate 26 and beyondthe bearing portion 24 .of the gear member which is provided at itsouter end beyond the plate 26 with a driving projection 28 having atransverse groove 29 and a circular outer groove30 for seating a springholding ring 3| therein. Near the outer end of the shaft 1 is a drivingcollar '32 secured thereto by a key 33 and having a transverse groove 34corresponding to the groove 29 of the adjacent projection 28 so that .afrangible driving key or pin 35 may be inserted in the grooves 34 and 29connecting the driving member 22 and the'driving collar 32, the drivingpin being seated and held in the groove of the collar 32 by a spring 3|seated in the circular groove 36 overlying the driving pin.

At the extremity of the shaft 1 is a reduced threaded portion 31 .forreceiving a nut 38 which holds a washer 39 against the driving collar32, thus retaining it in place. A protector cap 40 extends over theprojecting end of the shaft 1 and encloses the frangible drivingconnection and the inner end of the cap is secured to a threadedextension of the end plate 26 so that in order to renew the frangiblepin 35 it is necessary only to remove the cap and to remove the springclamping rings 3| from their grooves 30 and 36, or if these rings aresplit, to turn them to the split portion whereupon the old key may be removed if necessary and a new one inserted, which is thereupon held inplace by returning the clamping rings to engagement therewith.

Near the bottom of the plate 26 is a removable plug 42 for draining oilfrom the crank case and also connected through the plate near the bottomis an oil cup 43 through which oil may be inserted up to the level ofthe cup opening for lubricating the gears. The rotation of the gearswithin the casing carries the lubricant upwardly for oiling all of thegears therein.

At the closed side of the casing the shaft 1 may be formed with abearing enlargement 44 engaged by a bearing member 45 seated in a recess46 and retained therein by a plate 41 through which the enlarged portion44 of the shaft extends, the inner side of the cap containing a greaseretainer 48 for preventing lubricant from exuding along this end of theshaft. This extremity of the shaft may be formed with a squared portion49 for any desired driving engagement.

In this construction the driving gears are contained entirely within thehousing, the high driving speed of the motor is reduced if desired bythe driving pulleys, and is then reduced by the worm and gear drive, andis further reduced by the differential gearing within the casing to thedesired speed which is obtained from the power transmitting end of theshaft. The driving gears are mounted upon the shaft which extendsthrough the casing at both ends and the shaft at one end has a frangibledriving connection easily accessible without interfering with theconnection of the gears within the casing. This reduction drive istherefore adapted to be installed as a complete driving unit, the amountof the reduction depending upon the size of the gears and the connectionof the driving pulleys.

I claim:

1. A reduction drive unit comprising a casing having a rotatable shaftmounted therein, a fixed internal gear in the casing concentric with theshaft, a gear mounted freely on the shaft in the casing having aneccentric central projection at one side, means to rotate the gear onthe shaft, a gear secured to the shaft having an internally toothedportion extending toward the other gear, and a differential gear memberrotatable upon the eccentric projection having two externally toothedportions, one engaging the fixed internal gear in the casing and theother engaging the teeth of the gear secured to the shaft, the hub ofthe gear secured to the shaft having a frangible connection with the endof the shaft to which it is secured.

2. In a reduction drive, a casing having a closure plate at one side, ashaft rotatable in the casing having its extremities extending throughthe plate and the opposite Wall of the casing, differential gearingmounted on the shaft in the casing and means for driving it, the gearingincluding an end gear member with a concentric hub projection fittingand extending through an opening in the closure plate to form a bearingfor the adjacent end of the shaft, the wall of the casing forming thebearing for the other end of the shaft, and means outside of saidclosure plate connecting the shaft and the projecting end of the hub.

3. In a reduction drive, a gear casing having a reducing gear traintherein and means for driving it, a shaft upon which gears in the casingare mounted having its ends projecting through opposite sides of thecasing, the last gear of the train having a hub portion extendingoutside of the casing adjacent one end of the shaft, a collar secured tothis end of the shaft adjacent the said hub portion, the collar and hubportions having registering transverse slots, and a frangible drive pinseated in the slots for holding the gear to the shaft, the shaft drivingconnection being at the other end.

4. A reduction drive in accordance with claim 3 in which the said collarand hub portions are formed with outer grooves in which spring rings areseated for engaging and holding the frangible drive pin in the saidslots.

5. A reduction drive in accordance with claim 3 in which the casing atthe drive pin end is provided with a threaded portion surrounding theshaft, and a cap is threaded thereon to cover the end of the shaft andthe drive pin connection which is accessible by removing the cap Withoutinterfering with the driving connection of the shaft at the other end orwith the interior of the casing.

6. A reduction drive comprising a casing, a shaft extending through thecasing, a gear freely mounted on the shaft in the casing, a worm drivefor the gear, the gear having an eccentric projection at one side of thehub, a fixed internal gear in the casing concentric with the shaft, agear fixed to the shaft having an internal toothed portion overlying andof greater diameter than the said eccentric projection, and a doublegear member mounted to rotate on the eccentric pro jection, one threadedportion to engage the internal gear of the casing and the other toengage the internal gear of the gear fixed to the shaft, the eccentricprojection maintaining the double gear in rolling engagement with bothinternal gears to cause a differential movement between the movable andfixed gears on the shaft, the gear fixed to the shaft having a frangibleconnection with the end of the shaft accessible at the end thereofwithout disturbing the gears.

7. In a reduction drive, a casing having an internal gear therein, ashaft rotatable in the casing concentric with the axis of the internalgear, a gear rotatable on the shaft having an eccentric hub projection,within the casing gear, a gear fixed to the shaft having an internalgear overlying the end of the eccentric hub, and a double gear mountedto rotate on the eccentric projection having one portion to engage thecasing gear and another smaller portion to engage the overlying internalgear, the eccentric projection keeping both double gear portions inrolling contact with the internal gears as the gear is rotated on theshaft and the reduction in speed given to the shaft depending upon thedifference in the number of teeth between the double gear portions andthe internal gears the gear fixed to the shaft having a hub forming abearing therefor and the end of the hub having a frangible connectionwith the end of the shaft outside of the bearing.

ABRAM KORFF'.

